1. Field of the Invention
The invention relates to a variable-reluctance electric motor, more particularly a motor comprising a stator ring made of ferromagnetic material and having poles provided with induction windings distributed into four equal groups, at least one rotor ring of ferrogmagnetic material provided with equidistant teeth cooperating with the stator windings, and switching means actuated by the rotation of the rotor so as to distribute the supply of the stator windings from a d.c. voltage source, the windings and switching means being actuated so that, during each advance of the rotor by one tooth pitch, each pole is subjected to two opposite switching operations and, from one group of poles to the next, the switching operations are staggered by a time equal to the time taken by the motor to advance by a quarter of a tooth pitch.
2. Description of the Prior Art
Motors of this kind have known advantages (e.g. as disclosed in U.S. Pat. No. 3,435,266 of Mar. 25, 1969 and No. 3,740,630 of June 19, 1973) with regard to the production of a constant torque at a variable speed.
However, such machines are frequently too noisy owing to the rapid variations in the stator currents and the magneto-mechanical forces. In addition, the high amplitude of the variations in current may interfere with the d.c. source. An object of the invention is to obviate these disadvantages.